The present invention relates to improvements in or relating to reciprocating pistons used in particular in heat engines and other industrial machines.
Heretofore known reciprocating pistons have a lateral surface or a periphery of the at least first bead which is smooth or more generally threaded more or less deeply with a view in particular to retain oil for facilitating the slide. These pistons also comprise a first ring which is housed in an annular groove of the first bead of the piston.
These known pistons present a certain number of drawbacks which are finally translated by a reduced life and a poor yield of the engine in which they are used. In fact, the piston is not balanced due to the too large clearance existing between its bead and the bore of the cylinder in which it slides, and it is subjected to considerable, harmful oscillations during usage. The friction of the piston is, in fact, for a major part, that of the first ring which is subjected, on its inner face, to a very high pressure produced by the driving fluids which are engaged in the chamber delimited between this inner face and the bottom of the groove in which the ring is housed. Furthermore, as the duration of service of an engine increases, deposits of carbon are formed on the inner face of the ring and in the bottom of the groove receiving it. This carbon may provoke, particularly during the greatest expansions of the pistons, the jamming of each ring between these walls, thus bringing about a deterioration at these rings and consequently a loss of yield of the engine and a limitation of the life of the piston.